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Chemical sensing apparatus and methods

  • US 5,512,882 A
  • Filed: 08/07/1991
  • Issued: 04/30/1996
  • Est. Priority Date: 08/07/1991
  • Status: Expired due to Fees
First Claim
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1. Apparatus for indicating the end of service life of a filter cartridge for removing vapors of a chemical species from respired air, including a sensor that comprises:

  • a polymer whose physical structure changes upon exposure to said chemical species,discrete electrically conductive elements at least partly separated by said polymer, andan impedance-measuring means for measuring the impedance between two of said conductive elements,wherein a change in said polymer'"'"'s physical structure upon exposure to said chemical species results in an increase in the impedance between said two conductive elements, andwherein the change in physical structure consists of partial or complete disintegration of said polymer.

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